Astronomy

exploring the

Astronomy

expanding universe

U

sing powerful instruments developed with NSF’s support, investigators are closing in on fundamental truths about the universe. The work of these scientists creates new knowledge about the Sun, leads to the discovery of planets around distant stars, and uncloaks the majestic subtlety of the universe.

Ever since Galileo

perfected thetelescope and made the stars seem closer to

Earth, scientists have been searching the heavens, asking fundamental questions about the universe and our place in it. Today’s astronomers are finding that they don’t have to go far for some of the answers. With major funding from NSF, some researchers are exploring the interior of the Sun by recording and studying sound waves generated near itssurface. Others are discovering planets around distant stars and expressing optimism about finding still more, some of which may resemble Earth. With sophisticated equipment and techniques, we humans are finally “seeing” what lurks at the center of the Milky Way, hidden from direct view. We are making profound progress in uncovering the origins of the universe, estimating when it all began, andlooking at its structure, including the more than 90 percent of its mass known today as “dark matter.”

Voyage to the Center of the Sun
Despite its relative proximity to Earth, the Sun has kept its distance, reluctant to reveal its secrets. Until recently, its inner workings were a mystery of cosmic proportions. For many years, researchers have known that deep in the Sun’s interior, 600 million tonsof hydrogen fuse into helium every second, radiating out the resulting energy. And while the mechanics of this conversion have been described in theory, the Sun’s interior has remained inaccessible. Now, however, the Sun is being “opened,” its internal structures probed, and its inner dynamics surveyed by NSF-supported scientists using investigative techniques—a branch of astronomy known ashelioseismology. “The Sun is the Rosetta stone for understanding other stars,” explains John Leibacher, an astronomer at the National Optical Astronomy Observatories in Tucson, Arizona, and director of the NSF-funded Global Oscillation Network Group, or GONG. The Rosetta stone is a tablet with an inscription written in Greek, Egyptian hieroglyphic, and Demonic. The stone’s discovery was the key todeciphering ancient Egyptian hieroglyphic and unlocking the secrets of that civilization. GONG researchers study the Sun by analyzing the sound waves that travel through it. Much as the waves produced by earthquakes and explosions roll through the Earth, these solar sound waves pass through the Sun’s gaseous mass and set its surface pulsating like a drumhead. With six telescopes set up around theEarth collecting data every minute, GONG scientists are learning about the Sun’s structure, dynamics, and magnetic field by measuring and characterizing these pulsations.

New Visions
“All of a sudden, astronomers have turned a big corner and glimpsed in the dim light of distant lampposts a universe more wondrous than they had previously known,” writes John Noble Wilford in the February 9, 1997,issue of the New York Times. “Other worlds are no longer the stuff of dreams and philosophic musings. They are out there, beckoning, with the potential to change forever humanity’s perspective on its place in the universe.” Wilford is describing research by NSF-funded astronomers Geoffrey W. Marcy and R. Paul Butler of San Francisco State University, who were among the first to discover planetsoutside our solar system. Wilford’s words highlight the excitement and wonder of research in astronomy. With these and other recent discoveries, astronomers and astrophysicists are taking a fresh look at the realities and mysteries of the universe. Indeed, all of humankind is learning how immense and complex is the space we inhabit. Yet as we start to understand some of the phenomena around us, many...